1. Field of the Invention
The present invention relates to a paper powder collector, a process cartridge and an image forming apparatus such as a laser printer.
2. Description of the Related Art
A laser printer or another image forming apparatus is fitted with a removable process cartridge which is removably mounted on a body of the image forming apparatus. This cartridge includes a toner container which contains toner, a developing roller which holds toner, and a photoconductor drum. As the photoconductor drum rotates, its cylindrical surface is evenly charged by an electrostatic charger. The laser printer also includes a scanner which emits a laser beam representing image data. The scanner scans the charged drum surface with the laser beam at high speed to form an electrostatic latent image on this surface. The formed latent image is developed by the toner on the developing roller to form a visible image on the photoconductor drum.
The laser printer includes a feed tray. While the paper fed from the feed tray passes between the photoconductor drum and a transfer roller, the visible image on the drum is transferred onto the paper.
The paper fed from the feed tray normally has paper powder adhering to it. Therefore, in order to ensure the creation of a high-grade image, the laser printer includes a paper powder collector for removing paper powder from the paper. The powder collector includes a powder collecting roller and a powder reservoir. The collecting roller is positioned in the paper path between the feed tray and the photoconductor drum to remove the paper powder from the paper in contact with this roller. The collected powder is retained in the powder reservoir. It may be desirable that the collecting roller be movable, or adjustable.
For example, the process cartridge of a laser printer of this type may include a paper powder collector, which can be attached to and detached from the printer together with this cartridge. The laser printer includes a drive roller supported by a shaft fixed to the printer frame. It is desirable that, when the process cartridge is mounted in the laser printer, the powder collecting roller of the powder collector engages with the drive roller to remove paper powder from the paper being fed between the rollers. In order to properly position the collecting roller relative to the drive roller, it is preferable that the collecting roller be movable to some extent when the process cartridge is mounted or removed. If the collecting roller is movable, however, the paper powder collected by this roller may scatter from the powder reservoir of the powder collector when the process cartridge is removed. This will dust the inside of the laser printer with paper powder.
It is an object of the present invention to provide a paper powder collector including a movable powder collecting roller and a powder reservoir, and ensuring that the paper powder collected by the roller does not scatter from the reservoir. It is another object to provide a process cartridge and an image forming apparatus each including such a paper powder collector.
In accordance with a first aspect of the present invention, a process cartridge is provided which is removably fitted to an image forming apparatus. The process cartridge includes a cartridge body and a paper powder collector for collecting paper powder on a record medium passing for image formation thereon in the image forming apparatus. The powder collector includes a powder collecting roller having a cylindrical surface for contacting with the record medium to collect paper powder on the medium. The powder collector also includes a powder reservoir for retaining the collected powder. The powder reservoir has an opening through which the collected powder enters the reservoir and which is substantially covered by the collecting roller. The collecting roller and the powder reservoir are movable together relative to the cartridge body when the cartridge is fitted to or removed from the image forming apparatus.
When the process cartridge is fitted to and removed from the image forming apparatus, the collecting roller and the powder reservoir move together relative to the cartridge body. Consequently, the paper powder collected by the collecting roller is kept from scattering out of the powder reservoir when the roller moves. Accordingly, the collecting roller can be securely positioned relative to the image forming apparatus, while the collected powder can be retained in the powder reservoir without scattering. When the process cartridge is removed from the image forming apparatus, the powder reservoir can be replaced with a new one. This facilitates the maintenance of the process cartridge.
The powder collector may further include a friction member contacting frictionally with the cylindrical surface of the collecting roller to charge the roller surface. The charged surface can effectively collect paper powder. The friction member and the collecting roller can move together relative to the image forming apparatus. This realizes always-stable frictional charging or electrification.
The friction member may be a sponge, which improves the charging of the roller surface, making the collection of paper powder more effective. The sponge may be made of urethane foam, which improves the charging of the roller surface and the durability of the friction member.
The powder collector may further include a scraper contacting with the cylindrical surface of the collecting roller to scrape the paper powder off the roller surface before the powder contacts with the friction member. The scraped powder is securely retained in the powder reservoir without entering the friction member. This prevents the friction member effectively from being deteriorated by paper powder entering it. It is consequently possible to realize stable frictional charging for a long time. The scraper and the collecting roller can move together relative to the image forming apparatus.
The scraper may include a flexible member in contact with the cylindrical surface of the collecting roller. The flexible member can closely contact with the collecting roller so as to more effectively scrape off the paper powder collected by the roller.
The cylindrical surface of the collecting roller may be coated with a layer containing fluorine, which improves the charging of the roller surface, making the collection of paper powder more effective.
The collecting roller may include a shaft grounded for stable charging of the cylindrical surface of this roller.
The powder reservoir may be pivotable relative to the image forming apparatus, and support the collecting roller. This simple mechanism makes it possible to move the collecting roller and the powder reservoir together.
In accordance with a second aspect of the present invention, an image forming apparatus is provided which includes a process cartridge which can be fitted thereto and removed therefrom and paper powder collector which is supported on the cartridge and collects paper powder on a record medium passing for image formation thereon in the image forming apparatus. The powder collector includes a powder collecting roller having a cylindrical surface for contacting with the record medium to collect paper powder on the medium. The powder collector also includes a powder reservoir for retaining the collected powder. The powder reservoir has an opening through which the collected powder enters the reservoir. The collecting roller substantially covers the reservoir opening. The collecting roller and the powder reservoir can move together relative to the cartridge.
The collecting roller can be securely positioned relative to the image forming apparatus, while the paper powder collected by the collecting roller can be securely retained in the powder reservoir without scattering. This prevents the inside of the image forming apparatus effectively from being dusted with scattering paper powder.
The image forming apparatus may further include a drive roller having a cylindrical surface for contacting with the cylindrical surface of the collecting roller when the process cartridge is fitted to the image forming apparatus. The drive roller is mounted in the image forming apparatus. The image forming apparatus may further include a pressing member for pressing the collecting roller against the drive roller when the process cartridge is fitted to the image forming apparatus. When the process cartridge is fitted to the image forming apparatus, the pressing member securely positions the collecting roller relative to the drive roller. Consequently, the collecting roller is kept in a good position in collecting paper powder on the record medium. It is therefore possible to remove paper powder stably.
The image forming apparatus may include a guide which is provided on a casing of the apparatus and guides the cartridge when the process cartridge is fitted to the image forming apparatus.
In accordance with a third aspect of the present invention, a paper powder collector is provided for collecting paper powder on a record medium for image formation. This powder collector includes a powder collecting roller for contacting with the record medium to collect the paper powder on the medium. The powder collector also includes a scraper for scraping off the collected powder. The scraper includes a flexible member in contact with the collecting roller. The powder collector further includes a powder reservoir for retaining the scraped powder.
While the collecting roller is rotating in contact with the record medium, the roller collects paper powder on the medium. The collected powder is scraped off by the scraper. The scraped powder is retained in the powder reservoir. Consequently, paper powder can be collected effectively by the collecting roller, and the collected powder can be retained effectively in the powder reservoir. The flexible member of the scraper can be in close contact with the collecting roller so as to effectively scrape off the collected powder.
In accordance with a fourth aspect of the present invention, another image forming apparatus is provided which includes a paper powder collector for collecting paper powder on a record medium passing for image formation in the image forming apparatus. The powder collector includes a powder collecting roller for contacting with the record medium to collect the paper powder on the medium. The powder collector also includes a scraper for scraping off the collected powder. The scraper includes a flexible member in contact with the collecting roller. The powder collector further includes a powder reservoir for retaining the scraped powder.
Paper powder can be collected effectively from the record medium by the collecting roller, and the collected powder can be retained effectively in the powder reservoir. This makes it possible to form a fine image on the record medium without paper powder.
The apparatus may further include a process cartridge which is removably fitted to the apparatus and on which the paper powder collector is provided. When the process cartridge is removed from the image forming apparatus, the powder reservoir can be replaced with a new one. This facilitates the maintenance of the process cartridge.